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Discussion Starter · #1 ·
I plan on turning up the governor on my GCV160 to ~3500 after I get a new blade, and I have a few questions regarding the GCV160 engine...

1a. Can the GCV190 carb be installed in place of the GCV160 carb?

1b. If yes, can one retain the Auto Choke System?

2. Can the GCV190 cam wheel be installed in place of the GCV160 cam wheel?

From what I can tell, the GCV160 and the GCV190 both use the same timing belt, valves, and rockers... but the cam wheels are different. I am hoping the GCV190 cam is larger [either in duration or lift, or both] , but still is a direct fit in place of the GCV160's cam wheel. There is a PDF on how to adjust the valves, so I am too worried about that part of it.

As mentioned earlier, I am going to turn the governor up... can one advance/retard the cam wheel? The cam wheel and timing belt both have teeth.
 

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Honda GC's aren't like car engines... if you change, advance or retard the cam wheel, it's going to run bad or not at all. the gcv190 carb may fit, but being for a larger engine, may run too rich and pull down performance. going off memory on the GC's i've tore down, the duration and lift is the same. and even if you did change the duration, it will run bad if you don't change the ignition timing, which is virtually impossible... unless you were to get an offset flywheel key which do not exist for that engine.
as far as the lighter blade goes, contact the people you bought it from and ask if they know the maximum RPM, or blade tip speed it can be run at... centrifugal force is very strong, and is also proportionate to the mass of the object.
 

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Discussion Starter · #3 ·
Honda GC's aren't like car engines... if you change, advance or retard the cam wheel, it's going to run bad or not at all. the gcv190 carb may fit, but being for a larger engine, may run too rich and pull down performance. going off memory on the GC's i've tore down, the duration and lift is the same. and even if you did change the duration, it will run bad if you don't change the ignition timing, which is virtually impossible... unless you were to get an offset flywheel key which do not exist for that engine.
as far as the lighter blade goes, contact the people you bought it from and ask if they know the maximum RPM, or blade tip speed it can be run at... centrifugal force is very strong, and is also proportionate to the mass of the object.
Thank you for the response.

I probably need to get it into my head that the little Craftsman mower is not a racecar. Lol. But it is an internal combustion engine, so certain principles remain nearly universal... although some things do not scale in a linear manner.

I, myself, appreciate torque over horsepower... I like the mechanical leverage of a long stroke crankshaft... I generally prefer overhead valve architecture... but, BUT, what I have is the smallest possible displacement, shortest possible stroke, overhead cam GCV160.

I could just get a bigger mower, but I am not going to do that. Since I don't have the raw torque, I have to go for average HP. I know I am going to raise the governor speed, and I really don't want to run out of fuel. Thus, my interest in the GCV190's carb... I don't know if a 13% increase in RPM's justifies installing a carb from an engine with 19% more displacement, but I really don't want to run out of fuel.

It is disappointing that the cam duration and lift is the same between the two, I wonder why they have separate part numbers. Actually, they dont. Huh. I could have sworn my original search(es) shown different part numbers for the GCV160 camshaft pulley and the GCV190 part. They apparently use the same cam wheel. That simplifies things, I suppose.

Good call on needing a new timing pickup on the flywheel if one was to advance/retard the cam. I am probably not going to mess with any of that since there is only one cam profile available. I guess I could still try retard this cam a tooth or two, since I am raising the governor speed... but I'm probably not going to. If the GCV190 cam had more duration, I would have been willing to advance it a tooth or two in an effort to keep torque where I want it. I think it would have been cool to see the difference between a small cam retarded a couple teeth versus a large cam advanced a few teeth. But, oh well.
 

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You won't need to retard or advance the cam at 3500RPM....3600 RPM is pretty much the standard max safe RPM for small engines, especially on push mowers, it's when you get into the 10,000 or more RPM's you'd need to think about changing timing for optimum performance, which no small engine is really built to withstand that except 2 strokes.
 

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Can the GCV190 carb be installed in place of the GCV160 carb?
There would be no need to swap carburetors. Just swap jet sizes.

You can gain a little power with a fatter main jet, but you can't go more than a few sizes up without messing up the stoichiometry. Honda jets are numbered by the aperture diameter in hundredths of a mm. So for an example, a GCV160 #62 jet is part 99101-124-0620 = 0.620mm = 0.0244"
 

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Discussion Starter · #7 ·
After doing a little math, a 5% increase in jet size may have actually been a little conservative... I probably should have went up 10%, and ordered the 0680 jet. As it turns out, I would probably need to spin my '160 to about 4K to average the same air/fuel requirements as a '190 at 3500rpms... that would be a ~15% increase in average engine speed.

I am dubious of revving to 4000rpms with an aluminum cylinder, and nothing is forcing me to spin the motor that high. I don't have uber-grass that is exceptionally hard to cut. It's just my morbid curiosity and desire to tinker. Trying to match the air/fuel load of the '190 @ 3500rpms is a completely arbitrary goalpost.

Might actually need that bigger carb, if I do decide to chase 4000rpms. Even if I can put a large enough jet in the '160 carb, I don't want to suck the bowl dry... carbs aren't really my thing, so I don't know if bowls running dry is really a problem... this whole mad scientist experiment is actually an attempt for me to better understand such things.

If I am increasing the main jet size 5-10%, should I also increase the pilot jet size an equal amount? A lesser amount? More than I increase the main jet? Does the pilot jet size even matter that much since it is low throttle operation, and the GCV160 has Auto Choke, and the pilot isn't adjustable anyways. Lol.

Looks like the '160 comes with a 0350 pilot jet... and they offer 0380 and 0400 pilot jets. I am thinking that +5% on the pilot jet, and +10% on the main jet would be a good place to start, but I don't know $#!+...
 

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I don't know if bowls running dry is really a problem...
Not going to happen...
should I also increase the pilot jet size an equal amount?
You could go up to the next listed size, if needed. The pilot jet is always providing fuel, and then the main jet adds on top of it as RPM increases. Think of your engine as an air pump. The throttle plate opens to allow additional air to be pumped, and the venturi creates vacuum that draws fuel through the jets (where the jets' venturis cause it to atomize), hopefully somewhere near 14.7:1.
 
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Discussion Starter · #9 ·
Thank you. It is good to know that I don't have to worry about the bowl running dry.

In the name of science, I think I am going to try the larger 0400 pilot jet, instead of the 0380. Having already ordered a new main jet that, in hindsight, may not be big enough... I will overcompensate by getting a pilot jet that may end up being too large. See where that gets me.
 

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Discussion Starter · #11 ·
The Honda website has the net power listed at 3600rpms, which is well above where they wish people to operate these machines... 3000rpms is the recommended operating speed to reduce warranty claims and maintain a reputation of reliability.
 

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The Honda website has the net power listed at 3600rpms, which is well above where they wish people to operate these machines... 3000rpms is the recommended operating speed to reduce warranty claims and maintain a reputation of reliability.
On a Honda mower with the GCV160, the maximum safe RPM is 3,100.
ENGINE
Model GCV160
Engine type 4-stroke, overhead-cam, single-cylinder, air-cooled
Displacement 9.8 cu in (160 cc)
Bore and stroke 2.52 x 1.97 in (64 x 50 mm)
Compression ratio 8.5:1
Ignition system Transistorized magneto
Maximum horsepower 5.5 bhp (4.1 kW) @ 3,600 rpm
Maximum torque 8.4 ft-lb (11.4 N•m) @ 2,500 rpm
MAINTENANCE
Fuel Unleaded gasoline with a pump octane rating of 86 or higher
Engine oil SAE 10W-30
Spark plug type
Regular:NGK - BP6ES
DENSO - W20EP-U
Resistor:NGK - BPR6ES
DENSO - W20EPR-U
Maximum governed speed2,950 ~ 3,100 rpm
Blade bolt torque 36 ~ 43 ft-lb (5.0 ~ 6.0 kg-m, 49 ~ 59 N•m)
 

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Discussion Starter · #13 ·
Safe is a subjective word. Lol.

Honestly, catastrophic failure of a lawnmower is less spectacular than mentos in Dr Pepper, so I am not too worried about exceeding what they recommend as the maximum safe operation speed.
 

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Discussion Starter · #14 ·
That being said, I do not aim to waste this little motor... and I am trying to do this "right"... assuming there is a correct way to exceed the manufacturer's recommended maximum safe operating speed by nearly 30%. Lol.

Anyways, I am probably going to order that 0400 pilot jet, and install it at the same time as the 0650 main jet. Then just tune the governor until it runs well with those carb jets, whatever RPM that may be [it will be checked with a tach].

Are Honda pilot screw threads relatively universal across their small carbs? I keep seeing these hand-adjustable pilot screws intended for go-karts and dirt bikes...
 

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Discussion Starter · #15 ·
Funny story... so I kind of took tabora's 0620 main jet example and assumed it was what was in my GCV160. It is not.

I actually went out to the garage and looked up my exact model... it, in fact, has either a 0550 or 0580 from the factory. So I jumped the gun when I ordered the 0650, assuming it would have a 0620 sitting in there right meow.

My original intent was to just install a GCV190 carb, and it just so happens that the GCV190 comes with either a 0620 or 0650 from the factory... nailed it!

So, the 0400 pilot jet is probably going to be alright. Hopefully I can find an adjustable pilot screw...
 

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Discussion Starter · #18 ·
Let's talk Emulsion Tubes... where the magic happens...

Changing jets is all well and good, but that main nozzle is ultimately what is going determine how close one is to optimal air/fuel mixture at any given rpm. The good news about push mowers is there is really only one speed they operate at when in use, so there is not a lot of mid-range/transitional tuning... so the main nozzles can be relatively simple in their design.

But how are they [main nozzles] measured/labeled?

How does one determine which nozzle to choose? Is there a rule of thumb for emulsion tubes... like less holes for more rpms, or whatever?
 

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If i remember right, the hole in the nozzle is actually bigger than the jet hole, so it shouldn't matter, and there aren't different sized nozzles.... the GCV190 does use 2 different nozzles but they appear cosmetically different, but functionally the same.
 

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But how are they [main nozzles] measured/labeled?

How does one determine which nozzle to choose? Is there a rule of thumb for emulsion tubes... like less holes for more rpms, or whatever?
The nozzle listed for the GCV160 in the mower application is: 16166-ZM0-003
 
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